A grating polarizing mirror is known from U.S. Pat. No. 6,680,799 B1, which couples one of the local polarization components of the incident wave to a mode of the multilayer of the corresponding polarization. This mode can be a true guided mode of an all-dielectric multilayer or a true mode of the multilayer experiencing losses at a metal surface adjacent to the multilayer or a leaky mode of an all-dielectric multilayer. A first problem faced by the device disclosed by document U.S. Pat. No. 6,680,799 B1 is that the spectral position of mode excitation by the grating strongly depends on the refractive index and thickness of the layers of the multilayer as well as on the grating depth and line/space ratio. A second problem is that the filtering out of a polarization relies upon mode excitation which is inherently accompanied by a field enhancement in some layers of the multilayer, therefore to a possible degradation of the laser damage threshold in case the polarizing mirror is used in a high power laser.
Another polarizing mirror is known from EP 0798574 A2, which enhances the reflection coefficient of one of the polarization components of the incident wave by destructive interference of the corresponding polarization in the transmission medium whereas the orthogonal polarization gets partially transmitted. A first problem faced by this device is that it is difficult to fabricate the needed deep and well controlled line/space ratio binary corrugation. A second problem is that, in a laser application, the needed high index substrate is located within the laser cavity which can give rise to undesired thermal lensing if not to a degradation of the laser damage threshold if the substrate is made in a semiconductor material like GaAs. A third problem is that the high, possibly 100% reflection coefficient of the desired polarization is accompanied by a strong field enhancement in the corrugation region which may lead to a degradation of the laser damage threshold.